Syngas production from pyrolysis-catalytic steam reforming of waste biomass in a continuous screw kiln reactor

A two-stage continuous screw-kiln reactor was investigated for the production of synthesis gas (syngas) from the pyrolysis of biomass in the form of waste wood and subsequent catalytic steam reforming of the pyrolysis oils and gases. Four nickel based catalysts; NiO/Al₂O₃, NiO/CeO₂/Al₂O₃, NiO/SiO₂ (prepared by an incipient wetness method) and another NiO/SiO₂ (prepared by a sol-gel method), were synthesized and used in the catalytic steam reforming process. Pyrolysis of the biomass at a rapid heating rate of approximately 40°C/s, was carried out at a pyrolysis temperature of 500°C and the second stage reforming of the evolved pyrolysis gases was carried out with a catalytic bed kept at a temperature of 760°C. Gases were analysed using gas chromatography while the fresh and reacted catalyst was analysed by scanning electron microscopy, thermogravimetric analysis, transmission electron microscopy with energy dispersive X-ray and X-ray photoelectron spectroscopy. The reactor design was shown to be effective for the pyrolysis and catalytic steam reforming of biomass with a maximum syngas yield of 54.0 wt.% produced when the sol-gel prepared NiO/SiO₂ catalyst was used, which had the highest surface area of 765 m² g^-1. The maximum H ₂ production of 44.4 vol.% was obtained when the NiO/Al ₂O₃ catalyst was used.